[Bigdav160]

No longer have my K5 but I drive it's big brother K20 Suburban.

I like the 4L60 overdrive. Lower first gear for better take off. Overdrive for less stressed engine. Small increase in fuel economy but having the engine last longer has it's benefit. Quieter in the cabin too.

Moving the engine forward isn't a terrible task. Shorten the radiator hoses and lengthen the exhaust pipes.